In recent years, various functions are mounted in a mobile communication device such as a mobile phone and a communication system using mobile communication devices. One of such functions is a risk aversion function.
For example, Patent Literature 1 discloses a safety information providing device that gathers safety information and disaster information from predetermine domestic and local organizations, calculates reliability of the gathered safety information, and provides users with only safety information with reliability that is equal to or larger than a predetermined value. Patent Literature 1 also proposes a method of informing a user that the user is approaching a dangerous area by means of an alarm.
Patent Literature 2 discloses an identification tag to be connected to an external connection terminal of a mobile phone whereby allowing to make a phone call to a predetermined contact person. Although this is not an example of a mobile communication device, Patent Literature 3 discloses a crime prevention system that transmits a signal from an open/close sensor over a wireless digital signal wave.